In a suspension apparatus of a vehicle, for example, an upper link and a lower link are controlled to protrude or to retract by an actuator, thereby restraining variations in camber angle and tread of a wheel caused by bumping and rebounding in order to enhance steering stability performance (see, e.g., JP 6-047388 B2). The actuator includes a motor and a feed screw mechanism in which a male screw member is relatively rotated with respect to a female screw member by the motor.
In this type of actuator having a feed screw mechanism, in a case where some kind of abnormality occurs in relation to a control of the motor, the male screw member needs to be prevented from being separated from the female screw member, and an output rod needs to be prevented from dropping off from a housing. Thus, it is necessary to provide a stopper to limit the protrusion and retraction of the output rod at certain positions. However, when the stopper is provided, there is a problem that a size of the actuator increases.